EP1156600A1 - Cdma terminal and cdma method - Google Patents

Abstract

A data reception power measuring device 108measures reception power of a data section. A TPCbit reception power measuring device 109 measuresreception power of a forward TPC bit section. A pilotchannel reception power measuring device 110measures reception power of a pilot channel. Areception power measuring device 111 measuresreception power where an amount corresponding tovariation in transmission power is corrected by useof output signals from the data reception powermeasuring device 108, TPC bit reception powermeasuring device 109 and pilot channel receptionpower measuring device 110. A TPC bit generator 112compares reception power output from the receptionpower measuring device 111 with a threshold, whichis preset to satisfy a desired quality, wherebygenerating a reverse TPC bit, which instructs a basestation to increase/decrease transmission power.This makes it possible to perform high accuratemeasurement of reception power with respect to thesignal where transmission power varies according tothe variable rate, and to carry out transmissionpower control appropriately based on the measurementresult.

Description

Technical Field
• The present invention relates to a CDMAcommunication terminal apparatus and a CDMAcommunication method, which are used in a cellularsystem such as a digital car phone, a digital cellularphone, and the like.
Background Art
• A CDMA (Code Division Multiple Access) is asystem for spreading information to a sufficientlywide band as compared with a minimum band width atthe time of transmitting information. Moreover,CDMA is a communication system having excellentprivacy, concealment, SIR (Signal to InterferenceRatio), and is capable of increasing spectrumefficiency highly, and accommodating numerous usersas compared with FDMA (Frequency Division MultipleAccess) and TDMA (Time Division Multiple Access).
• In CDMA, however, there is a near-far problem,specifically, in the case where a desired stationis located at a far place and an undesired station(interference station) is located at a near place,reception power of a signal transmitted from the interference station is more increased thanreception power of a signal transmitted from thedesired station. This makes it impossible to suppresscross-correlation between spread codes by only aprocessing gain (spread gain) to make it impossibleto perform communications.
• Hence, a cellular system using CDMA needstransmission power control according to a state ofeach transmission channel in a reverse link, whichis from a mobile station to a base station. Moreover,a method for making compensation for variation ina momentary value of reception power by controllingtransmission power can be considered as measuresagainst fading, which is a cause of deterioratingchannel quality in a terrestrial mobilecommunication.
• Patent Publication No. HEI 4-502841 describesone example of a transmission power control methodin a cellular system using CDMA.
• FIG. 1 is a block diagram illustrating theconfigurations of abase station 10 and amobilestation 20 in a conventional CDMA communicationsystem described in the above publication. Normally,in the CDMA communication system, radiocommunications are performed between a plurality ofmobile stations 20 and onebase station 10.
• The following will explain the function of eachcomponent of thebase station 10. Ananalog receiver 12 provides processing such as amplification,frequency conversion, and the like to a multiplesignal, which is received by anantenna 11 and whichis sent from the plurality ofmobile stations 20,and theanalog receiver 12 supplies the resultantto adigital receiver 13 for eachmobile station 20.
• Thedigital receiver 13 detects correlationusing a spread code employed in themobile station20 that performs reception, whereby separating thesignal of themobile station 20 from the receivedsignals multiplied, and supplies the separatedsignal to abaseband processing circuit 14 and areceptionpower detecting circuit 15.
• Thebaseband processing circuit 14 obtainsreception data from the separated signal, andsupplies transmission data to themobile station 20,serving as a transmission signal, to amodulator 16.
• The receptionpower detecting circuit 15measures the level of the signal received from themobile station 20 and generates a transmission powercontrol (hereinafter referred to as "TPC") bit, andsupplies the generated TPC bit to themodulator 16.This TPC bit is used to control transmission powerof themobile station 20.
• Themodulator 16 multiplies the transmissionsignal from thebaseband processing circuit 14 andthe TPC bit from the receptionpower detectingcircuit 15 by a spread code assigned to themobile station 20, and outputs the resultant to anadder17.
• Theadder 17 multiplexes a spread signaloutputted from themodulator 16 for the pluralityofmobile stations 20. The signal multiplexed by theadder 17 is subjected to processing such as FR (RadioFrequency) conversion, amplification, and the like,and the resultant signal is transmitted as a radiosignal.
• The following will explain the function of eachcomponent of thebase station 10. Ananalog receiver22 provides processing such as amplification,frequency conversion, and the like to a multiplesignal, which is received by anantenna 21 and whichis sent from thebase station 10, and theanalogreceiver 22 supplies the resultant to adigitalreceiver 23. Moreover, theanalog receiver 22 hasa measuring circuit of an integrated power level ofthe received signal, and supplies the measured powerlevel to a transmissionlevel control circuit 26.
• Thedigital receiver 23 separates a signaladdressed to thedigital receiver 23 from the spreadand multiplexed signal by use of correction detection,and thedigital receiver 23 supplies the resultantto abaseband processing circuit 24. Moreover, thedigital receiver 23 extracts a TPC bit from theseparated signal, and supplies the extracted TPC bitto the transmissionlevel control circuit 26.
• Thebaseband processing circuit 24 obtainsreceived data from the separated signal.Concurrently, thebaseband processing circuit 24supplies transmission signal to thebase station 10,serving as a transmission signal, to amodulator 25.
• Themodulator 25 spreads the transmissionsignal from thebaseband processing circuit 24 usingan assigned spread code, and supplies the resultantto a transmissionlevel control circuit 26.
• The transmissionlevel control circuit 26controls transmission power of the spread signalusing the integrated power level from theanalogreceiver 22 and the TPC bit extracted from thereceived signal. An output signal of the transmissionlevel control circuit 26 is subjected to RFconversion, amplification, and the like andtransmitted as a radio signal from theantenna 21.
• In the transmission power control method in theaforementioned CDMA communication system, first,the transmission power level is controlled using theintegrated power level measured at theanalogreceiver 22 of themobile station 20, and thiscompensates for variation in a central value ofreception power of the base station, which is causedby a change in a distance between thebase station10 and the movedmobile station 20. This method isreferred to as transmission power control method dueto an open loop.
• Moreover, in order to increase the transmissionlevel of themobile station 20 when reception power,which is measured by the receptionpower detectingcircuit 15 of thebase station 10 and which is sentfrom themobile station 20, is lower than a presetreference level, and to decrease the transmissionlevel of themobiles station 20 when reception poweris higher than the reference level, the TPC bit isdetermined and transmitted to themobile station 20.
• Themobile station 20 controls the transmissionlevel using the TPC bit extracted by thedigitalreceiver 23 at a period of about 1.25 ms at high speed,and this compensates for variation in a momentaryvalue up to about several tens of Hz due to fadingin a reverse link, which is from themobile station20 to thebase station 10, and different fading ina forward link vice versa. This method is referredto as transmission power control method due to aclosed loop.
• As mentioned above, according to CDMA, thereis used the transmission power control method dueto the open loop and the closed loop in the reverselink.
• Additionally, the closed loop transmissionpower control in the reverse link is performed usingSIR (Desired signal to Interference signal Ratio)at the base station, making it possible to improvespectrum efficiency as compared with the case using reception power.
• While, in the forward link, this is no near-farproblem occurs unlike the reverse link. However, theclosed loop transmission power control is appliedto the forward link, making it possible to compensatefor variation in the momentary value of receptionpower due to fading and to improve the channelquality.
• Herein, in speech communication, there issometimes used a variable rate speech coding systemthat changes transmission speech data rate accordingto the state of the voice/unvoice sound and reducestransmission power per user on average in order toincrease the number of accommodation channels.
• In the case where the variable rate speech codingsystem is used in the forward link of CDMAcommunication system, transmission power of a datasection is changed depending on the rate. However,transmission power of TPC bit is made constant inorder to maintain the quality of TPC bit constantat themobile station 20.
• FIG. 2A to FIG. 2D are transmission signalpower views in the variable rate speech codingsystem.
• As illustrated in FIG. 2A to FIG. 2D, speechcoding data (transmission data) 31 to 34 isframe-configured in unit of about 20 ms, and the rateis changed on a frame-by-frame basis in accordance with the presence or absence of the sound. Then,transmission power is also changed in accordance withthe rate that changes in order of maximum rate (FIG.2A), 1/2 rate (FIG. 2B), 1/4 rate (FIG. 2C), and 1/8rate (FIG. 2D), and this makes it possible to reduceinterference with other user. Additionally, even iftransmission power is reduced when the rate is low,transmission power per information bit is maintained,so that no deterioration of quality occurs. On theother hand, aTPC bit 35 is periodically insertedand transmission power is unchanged even if the rateis changed.
• According to the conventional apparatus, in thecase where closed loop transmission power controlis applied to compensate for fading in the forwardlink, reception power of the forward link or SIR mustbe measured at a fixed period with a slow delay atthemobile station 20.
• However, in the case where transmission poweris changed in accordance with the change in the ratein the forward link, there is a problem in which themobile station 20 cannot determine whether the changein measured reception power is caused by propagationloss of radio propagation path or the change in therate.
• On the other hand, transmission power of TPCbit is fixed regardless of the rate, and propagationloss can be theoretically estimated based on reception power of TPC bit. However, since TPC bitis transmitted at a rate of only one bit per one slot(1.25 ms), there is a limitation in the estimationof accuracy of propagation loss, which is based onreception power of TPC bit. This causes a problemin which appropriate control cannot be carried outeven if transmission power control is performedaccording to the estimation result.
Disclosure of Invention
• It is an object of the present invention is toprovide a CDMA communication terminal apparatus,which is capable of measuring reception power withrespect to a signal where transmission power changesaccording to a variable rate and which is capableof performing transmission power controlappropriately based on the measurement result, anda CDMA communication method.
• The above object can be attained by adding anamount, corresponding to variation in receptionpower of a pilot channel, to reception power of aprevious slot where an amount corresponding tovariation in transmission power is corrected toobtain reception power.
Brief Description of Drawings
• FIG. 1 is a block diagram illustrating theconfiguration of a conventional CDMA communication system;
• FIG. 2A is a conceptual view of variable ratetransmission in the conventional CDMA communicationsystem;
• FIG. 2B is a conceptual view of variable ratetransmission in the conventional CDMA communicationsystem;
• FIG. 2C is a conceptual view of variable ratetransmission in the conventional CDMA communicationsystem;
• FIG. 2D is a conceptual view of variable ratetransmission in the conventional CDMA communicationsystem;
• FIG. 3 is a block diagram illustrating theconfiguration of a mobile station in a CDMAcommunication system according to the firstembodiment of the present invention;
• FIG. 4A is a conceptual view of a reception powermeasuring method at the mobile station in the CDMAcommunication system according to the firstembodiment of the present invention;
• FIG. 4B is a conceptual view of a reception powermeasuring method at the mobile station in the CDMAcommunication system according to the firstembodiment of the present invention;
• FIG. 5 is a block diagram illustrating theconfiguration of a mobile station in a CDMAcommunication system according to the second embodiment of the present invention; and
• FIG. 6 is a block diagram illustrating theconfiguration of a mobile station in a CDMAcommunication system according to the thirdembodiment of the present invention.
Best Mode for Carrying Out the Invention
• Generally, a cellular system using CDMA adoptsa method in which all mobile stations, which transmitan unmodulated pilot channel and performcommunication with the base station in the forwardlink from the base station to the mobile station,estimate a channel for receiving the pilot channelto demodulate data, and capture timingsynchronization of spread code, and hold it.
• Transmission power of the pilot channel is fixed.Moreover, since the pilot channel and the TPC bitpass through the same propagation path, theirvariations are equal to each other.
• Then, the TPC bit is transmitted at a rate ofonly one bit per one slot, while the pilot channelis transmitted with fixed power over the entiretyof the slots.
• The present invention focuses attention on theabove point.
• The following will specifically explain theembodiments of the present invention with referenceto the drawings accompanying herewith.
(Embodiment 1)
• FIG. 3 is a block diagram illustrating theconfiguration of the CDMA communication terminalapparatus according toEmbodiment 1 of the presentinvention. The following will explain the functionof each of components of a CDMAcommunicationterminal apparatus 100.
• Anantenna 101 receives a radio signaltransmitted from a base station, which is acommunication partner, and transmits a signaloutputted from atransmission RF section 117 as aradio signal.
• Areception RF section 102 performs frequencyconversion and amplification to the signal receivedby theantenna 101. AnAD converter 103 converts theanalog signal outputted from thereception RF section102 to a digital signal.
• Adata correlator 104 despreads the outputsignal of theAD converter 103 using the same spreadcode for data multiplied at the base station, andoutputs the resultant to a data receptionpowermeasuring device 108 and a TPC bit receptionpowermeasuring device 109.
• Apilot channel correlator 105 despreads theoutput signal of theAD converter 103 using a spreadcode for a pilot channel, and outputs the resultantto ademodulator 106 and a pilot channel receptionpower measuring device 110.
• Thedemodulator 106 provides processing suchas demodulation and multipath combining and the liketo the output signal of the data correlator 104 basedon the output signal of thepilot channel correlator105, and outputs the resultant to adecoder 107. Thedecoder 107 decodes an input signal from thedemodulator 106 to obtain received data.
• The data receptionpower measuring device 108measures reception power of a data section of thesignal outputted from the data correlator 104, andoutputs the resultant to a receptionpower measuringdevice 111. The TPC bit receptionpower measuringdevice 109 measures reception power of a forward TPCbit section of the signal outputted from the datacorrelator 104, and outputs the resultant to thereceptionpower measuring device 111. The pilotchannel receptionpower measuring device 110measures reception power of the pilot channeloutputted from the data correlator 105, and outputsthe resultant to the receptionpower measuring device111.
• The receptionpower measuring device 111measures reception power where an amountcorresponding to variation in transmission power iscorrected (hereinafter referred as "correctedreception power) using the output signals from thedata receptionpower measuring device 108, the TPCbit receptionpower measuring device 109, and the pilot channel receptionpower measuring device 110,and outputs the resultant to aTPC bit generator 112.A detailed explanation of a reception power measuringoperation at the receptionpower measuring device111 will be given later.
• TheTPC bit generator 112 compares receptionpower outputted from the receptionpower measuringdevice 111 with a threshold value, which is presetto satisfy a desired quality, and generates a reverseTPC bit, which instructs the base station toincrease/decrease transmission power. Then, theTPCbit generator 112 outputs the resultant to aframeconfiguring section 114.
• Acoder 113 provides processing such as an errorcorrection coding and the like to transmission datathat is transmitted to the base station, and outputsthe resultant to theframe configuring section 114.Theframe configuring section 114 multiplexes theoutput signal of thecoder 113 and that of theTPCbit generator 112, and outputs the resultant to aspreader 115 as transmission frame data. Thespreader115 provides spread processing to transmission framedata outputted from theframe configuring section114, and outputs the resultant to aDA converter 116.TheDA converter 116 coverts the digital signalsubjected to spread processing by thespreader 115to an analog signal, and outputs the resultant toatransmission RF section 117. Thetransmission RF section 117 provides frequency conversion andamplification processing to the analog signaloutputted from theDA converter 116, and outputs theresultant to anantenna 101.
• An explanation will be next given of theoperation of the CDMAcommunication terminalapparatus 100 having the above configuration.
• The signal, which is transmitted from the basestation and which is received by theantenna 101,is subjected to frequency conversion andamplification at thereception RF section 102.Thereafter, the resultant is converted to a digitalsignal (data) at theAD converter 103, and theresultant is outputted to the data correlator 104and thepilot channel correlator 105.
• The data correlator 104 performs despreadingby use of the same spread code for data multipliedat the base station, and outputs the resultant tothedemodulator 106, the data receptionpowermeasuring device 108, and the TPC bit receptionpowermeasuring device 109.
• Thepilot channel correlator 105 despreads thereceived signal subjected to AD conversion using thespread code for a pilot signal, and outputs theresultant to thedemodulator 106 and the pilotchannel receptionpower measuring device 110.
• Thedemodulator 106 provides processing suchas demodulation and multipath combining to data outputted from the data correlator 104 based on theoutput timing of thepilot channel correlator 105.Thereafter, thedemodulator 106 outputs theresultant to thedemodulator 107. Thedemodulator107 decodes data outputted from thedemodulator 106,whereby outputting received data.
• The data receptionpower measuring device 108measures reception power of the data section of thesignal outputted from the data correlator 104, andoutputs the resultant to the receptionpowermeasuring section 111. The pilot channel receptionpower measuring device 110 measures reception powerof the pilot channel outputted from the datacorrelator 105, and outputs the resultant to thereceptionpower measuring device 111.
• The receptionpower measuring device 111obtains corrected reception power based on receptionpower of the TPC bit section, reception power of thedata section, and reception power of the pilotchannel, and outputs the resultant to theTPC bitgenerator 112.
• TheTPC bit generator 112 compares receptionpower output therefrom with a threshold value, whichis preset to satisfy a desired quality, and generatesa reverse TPC bit, which instructs the base stationto increase/decrease transmission power. TheTPC bitgenerator 112 outputs the resultant to theframeconfiguring section 114.
• Thecoder 113 provides processing such as anerror correction coding and the like to transmissiondata that is transmitted to the base station, andoutputs the resultant to theframe configuringsection 114. Theframe configuring section 114multiplexes the output signal of thecoder 113 andthat of theTPC bit generator 112, and outputs theresultant to thespreader 115 as transmission framedata. This transmission frame data is subjected tospread processing at thespreader 115, the resultantis converted to an analog signal at theDA converter116, and the analog signal is subjected to frequencyconversion and amplification at thetransmission RFsection 117. Then, the resultant is transmitted tothe base station from theantenna 101 as a radiosignal.
• An explanation will be next given of thereception power measuring operation at the receptionpower measuring device 111 of the CDMAcommunicationterminal apparatus 100 with reference to FIG. 4A andFIG. 4B.
• FIG. 4A is a view of received signal power inwhich reception power of apilot channel 201outputted from the pilot channel receptionpowermeasuring device 110 is illustrated with a lapse oftime. FIG. 4B is a view of received signal powerin which reception power ofdata 202 outputted fromthe data receptionpower measuring device 108 and that of aTPC bit 203 outputted from the TPC bitreceptionpower measuring device 109 are illustratedwith a lapse of time. Additionally, in FIG.4A andFIG. 4B, one frame is composed of n slots (n is anatural number of 2 or more) and reception power ofthepilot channel 201 and that ofdata 202 are averagedover frame intervals.
• The receptionpower measuring device 111 firstaverages reception power ofdata 202 and theTPC bit203 over a frame interval whose rate is unchanged.Moreover, the receptionpower measuring device 111compares the average value of reception power ofdata202 with that of reception power of theTPC bit 203,and determines the rate of this frame.Data 202 andTPC bit 203 are averaged over the frame interval,whereby making it possible to obtain determinationaccuracy higher than the determining method at onlythe slot intervals.
• For example, in the case of frame A illustratedin FIG. 4A and FIG.4B, since the average value ofreception power ofdata 202 is about 1/2 of that ofreception power ofTPC bit 203, the rate is can bedetermined as 1/2.
• Then, the receptionpower measuring device 111multiplies the average value of reception power ofthe data section by the reciprocal number of thedetermined rate, and converts it to average receptionpower P₀ of frame A at a maximum rate conversion time. This makes it possible to correct the amountcorresponding to variation in the rate oftransmission power.
• Moreover, the receptionpower measuring device111 adds a difference in the reception power of thepilot channel to the corrected reception power ofthe previous slot to obtain reception power of adesired slot.
• For example, in FIG. 4, it is assumed that adifference between the reception power of the pilotchannel in the first slot of the frame B and thatof the pilot channel in nth slot of the frame B isPd₁. The receptionpower measuring device 111 obtainsreception power Pd₁ in the first slot of the frameB as an added value of P₀ and Pd₁.
• Sequentially, if average power in a differencebetween the average power of (i+1)th slot and theaverage power of ith slot, which is the differencebetween the slots in the average reception power ofthe pilot signal, is set to P_i+1, the receptionpowermeasuring device 111 obtains reception power P_i+1 of(i+1)th slot as an added value of reception powerP₁ and P_i+1 (i is a natural number of n-1 and less).
• Thus, the pilot channel is transmitted with afixed power over the entirety of slot intervals andthe variation in the pilot channel is equal to thedata section and the TPC bit. Hence, the differencein reception power of the pilot channel is added to the corrected reception power of the previous slotto obtain reception power of a desired slot, makingit possible to obtain a measurement value with highaccuracy. Transmission power control can beappropriately performed based on the measurementresult.
(Embodiment 2)
• FIG. 5 is a block diagram illustrating theconfiguration of the CDMA communication terminalapparatus according to Embodiment 2 of the presentinvention. Additionally, in a CDMAcommunicationterminal apparatus 300 illustrated in FIG. 5, thesame reference numerals as those of FIG. 3 are addedto the configuration parts common to the CDMAcommunication terminal apparatus 100 illustrated inFIG. 3, and the explanation is omitted.
• The CDMAcommunication terminal apparatus 300illustrated in FIG. 5 is different from the CDMAcommunication terminal apparatus 100 ofEmbodiment1 in the point that a receptionpower measuring device301 corrects the amount corresponding to variationin transmission power by use of the rate determinedby thedecoder 107.
• In such a configuration, thedecoder 107 mustdetermine the rate of received data at a decodingtime, and there is used a method for determining therate by use of error detection processing such asa CRC (Cyclic Redundancy Check) and the like after decoding on the assumption of all rates.
• Accordingly, the use of the reception signalrate determined by thedecoder 107 at the time ofmeasuring reception power makes it possible for thereceptionpower measuring device 301 to determinethe rate at high accuracy as compared with the caseexplained inEmbodiment 1 in which the rate isdetermined using the comparison between the frameaverage reception power of the data section and thatof the TPC bit.
• In this way, the receptionpower measuringdevice 301 corrects the amount corresponding to thevariation in transmission power using the ratedetermined by thedecoder 107, whereby receptionpower can be measured with high accuracy andtransmission power control can be appropriatelyperformed based on the measurement result.
(Embodiment 3)
• InEmbodiments 1 and 2, the difference in theaverage reception power between slots of the pilotchannel is added to the average corrected receptionpower of the frame. However, transmission power ofthe actual data channel is varied by control, whichis based on the reverse TPC bit transmitted from theCDMAcommunication terminal apparatus 400. Hence,the difference between transmission power of theactual data channel and the pilot channel transmittedwith a fixed power is generated by only the amount corresponding to variation due to control.Embodiment 3 explains the case in which this problemis solved so that reception power is measured withhigher accuracy.
• FIG. 6 is a block diagram illustrating theconfiguration of the CDMA communication terminalapparatus according to Embodiment 3 of the presentinvention. Additionally, in a CDMAcommunicationterminal apparatus 400 illustrated in FIG. 5, thesame reference numerals as those of FIG. 3 are addedto the configuration parts common to the CDMAcommunication terminal apparatus 100 illustrated inFIG. 3, and the explanation is omitted.
• The CDMAcommunication terminal apparatus 400illustrated in FIG. 6 is different from the CDMAcommunication terminal apparatus 100 ofEmbodiment1 in the point that a receptionpower measuring device401 performs measurement of reception power by useof the reverse TPC bit generated by theTPC bitgenerator 112.
• The amount corresponding to variation intransmission power of the base station can beestimated based on the reverse TPC bit transmittedfrom the CDMAcommunication terminal apparatus 400.
• Namely, theTPC bit generator 112 generates thereverse TPC bit, which instructs the base stationto increase/decrease transmission power, andoutputs the resultant to theframe configuring section 114 and the receptionpower measuring device401.
• The receptionpower measuring device 401 addsthe difference in the average reception power betweenslots of the pilot channel to the average correctedreception power of the frame. The receptionpowermeasuring device 401 further adds the amountcorresponding to variation in transmission power ofthe base station due to the reverse TPC bit thereto,whereby measuring reception power.
• Thus, at the time of measuring reception power,consideration is given to the amount correspondingto variation in transmission power of the basestation due to the reverse TPC bit, wherebycompensating for the difference between the datachannel and the pilot channel in transmission power,and this makes it possible to measure reception powerwith higher accuracy.
• Though the aforementioned embodiments haveexplained the case in which comparison betweenmeasured reception power and the threshold value isperformed to generate the reverse TPC bit, thepresent invention is not limited to this. SIR ismeasured and comparison between SIR and the thresholdvalue is performed so that the reverse TPC bit maybe generated.
• As is obvious from the above explanation,according to the present invention, high accurate measurement of reception power can be made withrespect to the signal where transmission power variesaccording to the variable rate, and transmissionpower control can be appropriately performed basedon the measurement result.
• This application is based on the Japanese PatentApplication No. HEI 11-366309 filed on December 24,1999, entire content of which is expresslyincorporated by reference herein.
Industrial Applicability
• The present invention is suitable for use ina cellular system such as a digital car phone, adigital cellular phone, and the like.

Claims (11)

1. A CDMA communication terminal apparatuscomprising:

   first measuring means for measuring receptionpower of variable rate data where transmission powervaries according to a transmission rate and thecontent of a reverse transmission power control bit;

   second measuring means for measuring receptionpower of an unmodulated pilot channel transmittedwith a fixed power; and

   reception power measuring means for measuringdesired signal reception power using said variablerate data where an amount corresponding to variationin transmission power is corrected and said receptionpower of the pilot channel.
2. The CDMA communication terminal apparatusaccording to claim 1, further comprising thirdmeasuring means for measuring reception power of areverse transmission power control bit whosetransmission power varies according to the contentof the reverse transmission power control bit,wherein said reception power measuring meanscompares average reception power of said reversetransmission power control bit at an interval whoserate is fixed with average reception power of thevariable rate data to determine a rate of saidvariable rate data, and corrects the amountcorresponding to variation in transmission power of said variable data using the determined rate.
3. The CDMA communication terminal apparatusaccording to claim 1, wherein said reception powermeasuring means corrects the amount correspondingto variation in transmission power of the variablerate using a rate determined by error detectionprocessing.
4. The CDMA communication terminal apparatusaccording to claim 1, wherein said reception powermeasuring means adds the amount corresponding tovariation in average reception power between theslots of the pilot channel to reception power of thevariable rate data where an amount corresponding tovariation in transmission power is corrected,whereby measuring desired signal reception power.
5. The CDMA communication terminal apparatusaccording to claim 1, wherein said reception powermeasuring means adds the amount corresponding tovariation in average reception power between theslots of the pilot channel and an amountcorresponding to variation in transmission power ofan apparatus of a transmitting side using the reversecontrol bit to reception power of the variable ratedata where an amount corresponding to variation intransmission power is corrected, whereby measuringdesired signal reception power.
6. The CDMA communication terminal apparatusaccording to claim 1, further comprising generating means for comparing the desired signal receptionpower measured by said reception power measuringmeans with a determined threshold value to generatea reverse transmission power bit, which instructsan apparatus of a transmitting side toincrease/decrease transmission power according tothe comparison result.
7. The CDMA communication terminal apparatusaccording to claim 1, said reception power measuringmeans comprises generating means for comparing aratio between desired wave reception power andinterference signal reception power with apredetermined threshold value to generate a reversetransmission power bit, which instructs an apparatusof a transmitting side to increase/decreasetransmission power according to the comparisonresult.
8. A CDMA communication method wherein a basestation apparatus, which performs radiocommunication with a communication terminalapparatus by CDMA, transmits an unmodulated pilotchannel with fixed power, and variable rate datawhere transmission power varies according to atransmission rate and a content of a reversetransmission power control bit by use of data channeladdressed to said communication terminal apparatus,and said communication terminal apparatus measuresdesired signal reception power by adding an amount corresponding to variation in reception power in saidpilot channel to reception power of said variablerate data after correcting the amount correspondingto variation in transmission power, and determinesa reverse transmission power control bit, whichcontrols transmission power of said base stationapparatus according to the relationship between saiddesired signal reception power and a predeterminedthreshold value in a value of large or small, andtransmits said determined reverse transmissionpower control bit.
9. The CDMA communication method according toclaim 8, wherein the base station apparatusmultiplexes a forward transmission power control bitwhere transmission power varies according to thecontent of a reverse transmission power control bitinto variable rate data in a time division mannerand transmits the variable rate data, and thecommunication terminal apparatus determines atransmission rate by comparing average receptionpower of said variable rate data at an interval whoserate is fixed with average reception power of thesaid forward transmission power control bit, andcorrects an amount corresponding to variation intransmission power based on the determinationresult.
10. The CDMA communication method according toclaim 8, wherein the base station apparatus adds an error detection coding signal to transmission dataand the communication terminal apparatus determinesa rate using said error detection code, and correctsan amount corresponding to variation in transmissionpower based on the determination result.
11. The CDMA communication method according toclaim 8, wherein the communication terminalapparatus determines the reverse transmission powercontrol bit using a value obtained by adding an amountcorresponding to variation in transmission power ofthe base station to the desired signal receptionpower measured.

Images